How do i put music on my blackberry?

[billy]

I have a blackberry bold 8900 and i have a 2gb memory card in it. my friend put a couple of songs on it for me by putting the mem card in a card reader but i don't have one and i was told that i can put songs on it by just using the usb charger that connects the blackberry to the computer, but when i tried it, there was no way of opening the files of the blackberry to put anything on it. if this is possible please tell me how to do it. thank you